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Abstract:

Disclosed herein are a piezoelectric vibration module and a touch screen
using the same. In the piezoelectric vibration module, a mass body is
attached to a central portion of a vibration bar, thereby making it
possible to maximize the amplitude of the piezoelectric vibration module,
and a groove is formed in the vibration bar to provide elasticity and
flexibility to the piezoelectric vibration module, thereby making it
possible to maximize vibratory force of the piezoelectric vibration
module. In the touch screen, the piezoelectric vibration module is
attached to a lower surface of an image display part of the touch screen,
thereby making it possible to directly transfer vibratory force generated
in the piezoelectric vibration module to an input unit.

Claims:

1. A piezoelectric vibration module comprising: a vibration bar; and a
pair of piezoelectric bodies formed at both sides on one surface of the
vibration bar based on a central portion of one surface of the vibration
bar.

2. The piezoelectric vibration module as set forth in claim 1, wherein
the vibration bar has a bar shape, such that it is vertically
reciprocatingly vibrated in a thickness direction thereof by the
shrinkage and expansion of the piezoelectric body.

3. The piezoelectric vibration module as set forth in claim 1, further
comprising a mass body attached to the central portion of the vibration
bar.

4. The piezoelectric vibration module as set forth in claim 1, further
comprising grooves formed at both ends of the vibration bar in a length
direction thereof so as to penetrate through the vibration bar in a
thickness direction thereof.

5. The piezoelectric vibration module as set forth in claim 1, wherein
the vibration bar is made of Invar.

6. The piezoelectric vibration module as set forth in claim 3, wherein
the mass body is formed to protrude to both sides of the vibration bar in
a width direction thereof.

7. The piezoelectric vibration module as set forth in claim 3, wherein
the mass body is made of steel use stainless (SUS) or tungsten (W).

8. The piezoelectric vibration module as set forth in claim 1, further
comprising a mass body attached to the central portion of the vibration
bar and grooves formed at both ends of the vibration bar in a length
direction thereof, wherein a position of the piezoelectric body attached
to one surface of the vibration bar is varied between the mass body and
the groove.

9. A touch screen using a piezoelectric vibration module, the touch
screen comprising: a touch screen panel; an image display part attached
to one surface of the touch screen panel; and the piezoelectric vibration
module including a vibration bar and a pair of piezoelectric bodies
formed at both sides on one surface of the vibration bar based on a
central portion of one surface of the vibration bar and directly attached
to one surface of the image display part.

10. The touch screen as set forth in claim 9, wherein the piezoelectric
vibration module further includes adhesive parts formed on the other
surface of the vibration bar, and the piezoelectric vibration module is
attached to the center of one surface of the image display part by the
adhesive parts.

11. The touch screen as set forth in claim 9, wherein the piezoelectric
vibration module further includes adhesive parts formed on the other
surface of the vibration bar, and the piezoelectric vibration module is
attached to the edge of one surface of the image display part by the
adhesive parts.

12. The touch screen as set forth in claim 9, wherein the piezoelectric
vibration module further includes adhesive parts formed on sides of the
vibration bar, and the piezoelectric vibration module is attached to the
center of one surface of the image display part by the adhesive parts.

13. The touch screen as set forth in claim 9, wherein the piezoelectric
vibration module further includes adhesive parts formed on sides of the
vibration bar, and the piezoelectric vibration module is attached to the
edge of one surface of the image display part by the adhesive parts.

14. The touch screen as set forth in claim 9, wherein the piezoelectric
vibration module further includes a mass body attached to the central
portion of the vibration bar.

15. The touch screen as set forth in claim 9, wherein the piezoelectric
vibration module further includes grooves formed at both ends of the
vibration bar in a length direction thereof so as to penetrate through
the vibration bar in a thickness direction thereof.

16. The touch screen as set forth in claim 9, wherein the vibration bar
is made of Invar.

17. The touch screen as set forth in claim 14, wherein the mass body is
formed to protrude to both sides of the vibration bar in a width
direction thereof.

18. The touch screen as set forth in claim 14, wherein the mass body is
made of steel use stainless (SUS) or tungsten (W).

19. The touch screen as set forth in claim 9, wherein the piezoelectric
vibration module further includes a mass body attached to the central
portion of the vibration bar and grooves formed at both ends of the
vibration bar in a length direction thereof, a position of the
piezoelectric body attached to one surface of the vibration bar being
varied between the mass body and the groove.

Description:

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of Korean Patent Application
No. 10-2011-0026016, filed on Mar. 23, 2011, entitled "Piezoelectric
Vibration Module And Touch Screen Using The Same", which is hereby
incorporated by reference in its entirety into this application.

BACKGROUND OF THE INVENTION

[0002] 1. Technical Field

[0003] The present invention relates to a piezoelectric vibration module
and a touch screen using the same.

[0004] 2. Description of the Related Art

[0005] In accordance with the development of a mobile communication
technology, terminals such as cellular phones, personal digital
assistances (PDAs), and navigations can serve as a unit that simply
displays character information as well as a unit for providing various
and complex multi-media such as audio, moving picture, radio internet web
browser, or the like. Therefore, electronic information terminals having
a limited size require a larger display screen, such that a display
device using a touch screen has become prominent.

[0006] Meanwhile, in a portable electronic device such as a portable
phone, a game machine, an e-book, or the like, a vibration function has
been employed as various uses. Particularly, a vibration generating
device performing the vibration function has been mounted in a mobile
device using the touch screen such as the portable phone, or the like,
such that it has been used as a receiving signal sensing function for a
transmitting signal.

[0007] As the vibration generating device is used in the touch screen, the
demand for a touch screen device allowing a user to immediately perceive
feedback vibration for his/her touch input has increased.

[0008] FIG. 1 is a cross-sectional view showing a structure of a touch
screen using a vibration generating device according to the prior art. A
touch screen 10 according to the prior art is configured to include a
touch screen panel 20, an image display part 30 attached to a lower
surface of the touch screen panel 20, and a vibration generating device
50 attached to an inside of an outer set 40 accommodating the touch
screen panel 20. As a to scheme of generating vibration according to the
prior art, a scheme of mounting the vibration generating device 50 such
as a vibration motor, a vibration actuator, or the like, in an inner
portion of the touch screen 10 of a cellular phone, etc., has been used.
Here, the vibration generating device 50 has been mounted inside the
outer set 40 of the touch screen 10.

[0009] In the touch screen 10, since the vibration generating device 50
has been mounted inside the outer set 40, when a signal input part is
operated using a finger or a touch pen, vibratory force of the vibration
generating device 50 has been not properly transferred to a part of the
touch screen panel 20 contacting the input unit.

[0010] Meanwhile, as the vibration generating device 50 according to the
prior art, a vibration motor, a vibration actuator, or the like, has been
mainly used. The vibration generating device 50 according to the prior
art had a difficulty in being designed to have a thin thickness, such
that it had a technical problem in being directly attached to a lower
surface of the image display part 30.

SUMMARY OF THE INVENTION

[0011] The present invention has been made in an effort to provide a
piezoelectric vibration module having a structure capable of maximizing
vibratory force and also provide a touch screen capable of directly
transferring vibratory force generated in the piezoelectric vibration
module to an input unit by applying the piezoelectric vibration module to
the touch screen.

[0012] According to a first preferred embodiment of the present invention,
there is provided a piezoelectric vibration module including: a vibration
bar; and a pair of piezoelectric bodies formed at both sides on one
surface of the vibration bar based on a central portion of one surface of
the vibration bar.

[0013] The vibration bar may have a bar shape, such that it is vertically
reciprocatingly vibrated in a thickness direction thereof by the
shrinkage and expansion of the piezoelectric body.

[0014] The piezoelectric vibration module may further include a mass body
attached to the central portion of the vibration bar.

[0015] The piezoelectric vibration module may further include grooves
formed at both ends of the vibration bar in a length direction thereof so
as to penetrate through the vibration bar in a thickness direction
thereof.

[0016] The vibration bar may be made of Invar.

[0017] The mass body may be formed to protrude to both sides of the
vibration bar in a width direction thereof.

[0018] The mass body may be made of steel use stainless (SUS) or tungsten
(W).

[0019] The piezoelectric vibration module may further include a mass body
attached to the central portion of the vibration bar and grooves formed
at both ends of the vibration bar in a length direction thereof, wherein
a position of the piezoelectric body attached to one surface of the
vibration bar is varied between the mass body and the groove.

[0020] According to a second preferred embodiment of the present
invention, there is provided a touch screen using a piezoelectric
vibration module, the touch screen including: a touch screen panel; an
image display part attached to one surface of the touch screen panel; and
the piezoelectric vibration module including a vibration bar and a pair
of piezoelectric bodies formed at both sides on one surface of the
vibration bar based on a central portion of one surface of the vibration
bar and directly attached to one surface of the image display part.

[0021] The piezoelectric vibration module may further include adhesive
parts formed on the other surface of the vibration bar, and the
piezoelectric vibration module may be attached to the center of one
surface of the image display part by the adhesive parts.

[0022] The piezoelectric vibration module may further include adhesive
parts formed on the other surface of the vibration bar, and the
piezoelectric vibration module may be attached to the edge of one surface
of the image display part by the adhesive parts.

[0023] The piezoelectric vibration module may further include adhesive
parts formed on sides of the vibration bar, and the piezoelectric
vibration module may be attached to the center of one surface of the
image display part by the adhesive parts.

[0024] The piezoelectric vibration module may further include adhesive
parts formed on sides of the vibration bar, and the piezoelectric
vibration module may be attached to the edge of one surface of the image
display part by the adhesive parts.

[0025] The piezoelectric vibration module may further include a mass body
attached to the central portion of the vibration bar.

[0026] The piezoelectric vibration module may further include grooves
formed at both ends of the vibration bar in a length direction thereof so
as to penetrate through the vibration bar in a thickness direction
thereof.

[0027] The vibration bar may be made of Invar.

[0028] The mass body may be formed to protrude to both sides of the
vibration bar in a width direction thereof.

[0029] The mass body may be made of steel use stainless (SUS) or tungsten
(W).

[0030] The piezoelectric vibration module may further include a mass body
attached to the central portion of the vibration bar and grooves formed
at both ends of the vibration bar in a length direction thereof, wherein
a position of the piezoelectric body attached to one surface of the
vibration bar is varied between the mass body and the groove.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 is a cross-sectional view showing a structure of a touch
screen using a vibration generating device according to the prior art;

[0032] FIGS. 2 to 6 are cross-sectional views and plan views showing a
structure of a piezoelectric vibration module according to a preferred
embodiment of the present invention;

[0033] FIG. 7 is a simulation view showing deformation amount for each
position of a piezoelectric vibration module attached to an image display
part;

[0034] FIG. 8 is a graph showing displacement of a piezoelectric vibration
module according to frequency;

[0035] FIG. 9 is a cross-sectional view showing a structure of a touch
screen using a piezoelectric vibration module according to the present
invention; and

[0036] FIGS. 10 to 13 are views showing various attachment shapes of a
piezoelectric vibration module attached to an image display part.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] Various objects, advantages and features of the invention will
become apparent from the following description of embodiments with
reference to the accompanying drawings.

[0038] The terms and words used in the present specification and claims
should not be interpreted as being limited to typical meanings or
dictionary definitions, but should be interpreted as having meanings and
concepts relevant to the technical scope of the present invention based
on the rule according to which an inventor can appropriately define the
concept of the term to describe most appropriately the best method he or
she knows for carrying out the invention.

[0039] The above and other objects, features and advantages of the present
invention will be more clearly understood from the following detailed
description taken in conjunction with the accompanying drawings. In the
specification, in adding reference numerals to components throughout the
drawings, it is to be noted that like reference numerals designate like
components even though components are shown in different drawings.
Further, when it is determined that the detailed description of the known
art related to the present invention may obscure the gist of the present
invention, the detailed description thereof will be omitted.

[0040] Hereinafter, preferred embodiments of the present invention will be
described in detail with reference to the accompanying drawings.

[0041] Piezoelectric Vibration Module

[0042] FIGS. 2 to 6 are views showing a structure of a piezoelectric
vibration module according to a preferred embodiment of the present
invention. Hereinafter, a piezoelectric vibration module 100 according to
the present embodiment will be described with reference to FIGS. 2 to 6.

[0043] As shown in FIG. 2, the piezoelectric vibration module 100
according to a preferred embodiment of the present invention is
configured to include a vibration bar 110, and a pair of piezoelectric
bodies 120 formed at both sides on one surface of the vibration bar 110.

[0044] The vibration bar 110, which is a member subjected to the
shrinkage/expansion movement of the piezoelectric body 120 to thereby
generate vibration in the piezoelectric vibration module 100, has a
predetermined length (L), width (W), and thickness (T). In the
piezoelectric vibration motor according to the present invention, the
vibration bar 110 is vertically reciprocatingly moved in a thickness T
direction thereof, thereby transferring vibratory force to a contact
member (for example, a slider, a rotor, or an image display part 230 (See
FIG. 9)), or the like. Therefore, the vibration bar 110 has a bar shape
elongated in a length (L) direction thereof in order to maximize the
amplitude in the thickness (T) direction thereof.

[0045] Meanwhile, the vibration bar 110 is made of a metal having
excellent elastic force in order to prevent fatigue failure thereof due
to the reciprocating deformation thereof. Moreover, in order to reduce
thermal stress generated due to a difference in coefficients of thermal
expansion between the vibration bar 110 and the piezoelectric body 120, a
material having a coefficient of thermal expansion similar to that of the
piezoelectric body 120 is preferably selected as a material of the
vibration bar 120. The vibration bar may be made of, for example, steel
use stainless (SUS), Invar; however, a material of the vibration bar is
not specifically limited.

[0046] The piezoelectric body 120 is shrunk/expanded by the application of
a voltage and includes an electrode formed thereon. When a predetermined
set voltage is applied to the electrode, the piezoelectric body 120 is
flexurally vibrated while being shrunk or expanded, such that the
vibration bar 110 is entirely driven vertically.

[0047] The piezoelectric body 120 configuring the piezoelectric vibration
module 100 according to the present invention is formed on one surface of
the vibration bar 110. Basically, each of a pair of piezoelectric bodies
120 is disposed at both sides based on a central portion A of the
vibration bar 110 in a length (L) direction thereof. The piezoelectric
bodies 120 may be formed in a single layer structure at both sides of the
vibration bar 110. In addition, at least one piezoelectric body 120 may
be stacked in a multi-layer structure. When the piezoelectric bodies 120
are stacked in the multi-layer structure, even though a low voltage is
applied to the piezoelectric bodies 120, the driving force required for
driving the piezoelectric vibration module 100 may be implemented. In
addition, it is possible to form the piezoelectric bodies 120 in a
single-layer structure on the vibration bar 110 and dispose the
piezoelectric bodies 120 in parallel in a width (W) direction of the
vibration bar 110. When the number of piezoelectric bodies 120 formed on
the vibration bar 110 as described above increases, the entire vibratory
force of the piezoelectric vibration module 100 increase.

[0048] Meanwhile, each of the piezoelectric bodies 120 may be positioned
to be variable between a central portion A of the vibration bar 110 in a
length direction thereof and one end E in the length direction thereof;
however, is preferably positioned as closely as possible to the central
portion A. This is the reason that when the piezoelectric body 120 is
positioned at the center between the central portion A of the vibration
bar 110 and one end E thereof, the magnitudes of each moment generated at
both ends of the piezoelectric body 120 during shrinkage/expansion
movement of the piezoelectric body 120 correspond to each other, thereby
hindering the entire vertical reciprocating movement of the vibration
bar.

[0049] Meanwhile, the piezoelectric body 120 may be made of a
piezoelectric material such as a piezoelectric ceramic (PZT), a
piezoelectric crystal, or the like.

[0050] Meanwhile, the vibration bar 110 may have adhesive parts 130 formed
on the other surface thereof. The piezoelectric vibration module 100 is
attached to a lower surface of an image display part 230 (See FIG. 9) to
be described below by the adhesive parts 130. The adhesive part 130 may
also be attached to a side of the vibration bar 110 according to a shape
in which the piezoelectric vibration module 100 is attached to the image
display part 230.

[0051] As shown in FIGS. 3 to 6, the piezoelectric vibration module 100
may further include a mass body 140. Since the mass of the piezoelectric
vibration module 100 is concentrated on a point at which the driving
displacement thereof is maximized, the mass body 140 is attached to the
central portion of the vibration bar 110 to maximize mass eccentricity of
the piezoelectric vibration module 100, thereby contributing to
maximizing vibratory force of the piezoelectric vibration module 100. As
a material of the mass body 140, a material having high density is
preferably selected. Particularly, steel use stainless (SUS) or tungsten
(W) may be used.

[0052] Meanwhile, the mass body 140 is formed to have a width narrower
than that W of the vibration bar 110, such that it may be formed inside
the vibration bar 110 (See FIG. 3 or FIG. 5). Furthermore, the mass body
140 may also be formed to protrude to both sides of the vibration bar 110
in a width (W) direction thereof (See FIG. 4 or FIG. 6). This is to
increase mass of the mass body 140 attached to the central portion of the
vibration bar 110, thereby improving vibratory force.

[0053] As shown in FIGS. 5 and 6, the piezoelectric vibration module 100
may further include grooves 150. The grooves 150 are formed at both ends
of the vibration bar 110 in a length (L) direction thereof and penetrate
through the vibration bar 110 in a thickness (T) direction thereof. When
the groove 150 is formed, an elastic modulus (k) of the piezoelectric
vibration module 100 is reduced, thereby making it possible to increase
the amplitude of the vibration bar 110 with respect to the same input
voltage.

[0054] Meanwhile, when the piezoelectric vibration module 100 configured
of the vibration bar 110 and the piezoelectric bodies 120 is formed to
further include the mass body 140 attached to the central portion of the
vibration bar 110 and the grooves 150 formed at both ends of the
vibration bar 110 in the length (L) direction thereof, arrangement
positions of the piezoelectric bodies 120 attached to one surface of the
vibration bar 110 may be varied between the mass body 140 and the grooves
150.

[0055] A structure of the piezoelectric vibration module 100 in which the
mass body 140 is attached to the central portion of the vibration bar 110
and the piezoelectric bodies 120 are disposed at both sides based on the
mass body 140 is to maximize the vibratory force. FIG. 7 is a simulation
view showing deformation amount for each partial position of a
piezoelectric vibration module 100 when the piezoelectric vibration
module 100 is attached to an image display part 230 (See FIG. 9). The
piezoelectric vibration module 100 has adhesive parts 130 (See FIG. 2)
formed at both ends of the vibration bar 110 in a length (L) direction
thereof, and is attached to the image display part 230 by the adhesive
part 130. A bar shown at a lower side of FIG. 7 is shown with a dividing
shadow according to the deformation amount thereof. The deformation
amount (amplitude) becomes insignificant toward the left, and it becomes
significant toward the right. As shown in FIG. 7, the vibration bar 110
has the deformation amount increased toward the central portion thereof,
and has the maximum deformation amount at an area at which the mass body
140 is attached thereto. That is, the piezoelectric vibration module 100
according to the present invention has the mass body 140 disposed at a
part at which the deformation amount of the vibration bar 110 is
maximized, that is, the central portion of the vibration bar 110, thereby
making it possible to maximize the vibratory force applied to the image
display part 230. This is supported by the following vibratory force
calculating equation:

G={m(x)ω2}/M

[0056] Where G indicates strength of vibratory force, M indicates the
entire mass of the piezoelectric vibration module 100 and the image
display part 230, m indicates the sum of masses of actually vibrating
components in the piezoelectric vibration module 100, x indicates driving
displacement (amplitude), and ω indicates frequency. That is, the
mass body 140 having a predetermined mass is disposed at the central
portion of the vibration bar 110 at which the driving displacement (x) of
the piezoelectric vibration module 100 is maximized, thereby making it
possible to maximize the vibratory force (G).

[0057] Meanwhile, FIG. 8 is a graph showing driving displacement according
to frequency with respect to a piezoelectric vibration module 100
designed to have a specific specification. Here, the frequency of the
piezoelectric vibration module 100 may be controlled by the following
equation:

ω=(1/2π)* (k/m)

[0058] Where k indicates an elastic modulus (k) of the piezoelectric
vibration module 100, and m indicates mass of the piezoelectric vibration
module 100. The values of k and m are controlled, thereby making it
possible to design the piezoelectric vibration module 100 so as to have
frequency at which it may be driven at the maximum displacement thereof.

[0059] Touch Screen Using Piezoelectric Vibration Module

[0060] FIG. 9 is a cross-sectional view showing a structure of a touch
screen using a piezoelectric vibration module according to the present
invention.

[0061] As shown in FIG. 9, a touch screen 200 using a piezoelectric
vibration module 100 according to a preferred embodiment of the present
invention is configured to include a touch screen panel 220, an image
display part 230 attached to a lower surface of the touch screen panel
220, and a piezoelectric vibration module 100 including a vibration bar
110 and a pair of piezoelectric bodies 120 and directly attached to a
lower surface of the image display part 230. The touch screen panel 220
is mounted in an outer set 240. The touch screen 200 according to the
present invention uses a piezoelectric vibration module 100 disclosed in
claims 1 to 9 and a detailed description of the disclosure for the
piezoelectric vibration module 100, and the touch screen panel 220 and
the image display part 230 includes structures in all shapes known in the
prior art. Meanwhile, although FIGS. 10 to 13 show an image display part
having a rectangular shape by way of example, a shape of the image
display part 230 is not limited thereto. A touch screen 200 including an
image display part 230 having a polygonal shape or a circular shape may
be used.

[0062] An object of the present invention is to provide a touch screen 200
in which when the touch screen 200 is touched using an input unit,
vibratory force generated in a piezoelectric vibration module 100 is
directly transferred to the input unit. In the present invention, the
piezoelectric vibration module 100 is directly attached to the lower
surface of the image display part 230 in order to accomplish this object.

[0063] FIGS. 10 to 13 show various attachment shapes of a piezoelectric
vibration module 100 attached to an image display part 230.

[0064] In a first preferred embodiment, the piezoelectric vibration module
100 further includes adhesive parts(not shown) formed on the other
surface of the vibration bar 110 and is attached to the center of a lower
surface of the image display part 230 by the adhesive parts(not shown)
(See FIG. 10).

[0065] In a second preferred embodiment, the piezoelectric vibration
module 100 further includes adhesive parts(not shown) formed on the other
surface of the vibration bar 110 and is attached to the edge of a lower
surface of the image display part 230 by the adhesive parts(not
shown)(See FIG. 11). That is, when an image display part 230 having a
polygonal shape is used, a plurality of piezoelectric vibration modules
100 may be attached to an inner side of at least one edge of the lower
surface of the image display part 230, and when an image display part 230
having a circular shape is used, a plurality of piezoelectric vibration
modules 100 may be attached to the lower surface of the image display
part 230 so as to be spaced apart from each other by a predetermined
interval.

[0066] In a third preferred embodiment, the piezoelectric vibration module
100 further includes adhesive parts (not shown) formed on sides of the
vibration bar 110 and is attached to the center (FIG. 12) or the edge
(FIG. 13) of a lower surface of the image display part 230 by the
adhesive parts 130. In this case, vertical driving of the piezoelectric
vibration module 100 in a thickness (T) direction thereof induces
vibration of the image display part 230 in a horizontal direction.

[0067] The piezoelectric vibration module 100 is attached to the image
display part 230 in various shapes as described in the above-mentioned
preferred embodiments, thereby making it possible to implement vibration
of the image display part 230 in a horizontal direction or a vertical
direction thereof.

[0068] According to the present invention, the mass body is attached to
the central portion of the vibration bar, thereby making it possible to
maximize the amplitude of the piezoelectric vibration module, and the
groove is formed in the vibration bar to provide elasticity and
flexibility to the piezoelectric vibration module, thereby making it
possible to maximize vibratory force of the piezoelectric vibration
module.

[0069] In addition, according to the present invention, the piezoelectric
vibration module is attached to the lower surface of the image display
part configuring the touch screen, thereby making it possible to directly
transfer the vibratory force generated in the piezoelectric vibration
module to an input unit.

[0070] Although the preferred embodiments of the present invention have
been disclosed for illustrative purposes, they are for specifically
explaining the present invention and thus a piezoelectric vibration
module and a touch screen using the same according to the present
invention are not limited thereto, but those skilled in the art will
appreciate that various modifications, additions and substitutions are
possible, without departing from the scope and spirit of the invention as
disclosed in the accompanying claims.

[0071] Accordingly, such modifications, additions and substitutions should
also be understood to fall within the scope of the present invention.